VCE Methods Question Thread!

[Homer]

try eliminating variables froom the equations, and at the end i think you should end up with k can not equal to 5/3. correct me if im wrong, kinda rustyy :/

[Only Cheating Yourself]

try eliminating variables froom the equations, and at the end i think you should end up with k can not equal to 5/3. correct me if im wrong, kinda rustyy :/

I'm just trying to get k as the subject, i didn't quite understand you, I'm just confused as to why we used the reciprocal?

[Homer]

I'm just trying to get k as the subject, i didn't quite understand you, I'm just confused as to why we used the reciprocal?

oh i was replying to

Consider the following system of simultaneous equations:
6x+2y-z=1
x+y+z=2
kx+y-z=1

What values of k is there a unique solution?

[Only Cheating Yourself]

Consider the following system of simultaneous equations:
6x+2y-z=1
x+y+z=2
kx+y-z=1

What values of k is there a unique solution?

are you asking me?

[Lasercookie]

I'm just trying to get k as the subject, i didn't quite understand you, I'm just confused as to why we used the reciprocal?

One perspective would be along the lines of "Why did the chicken cross the road? To get the other side." We take the reciprocal because it's a valid step that gets us to the answer quickly. Why is it a valid step? Well because it does not alter the underlying relationship between the variables, it's simply rephrasing it in another sense. It's similar to multiplying one half of an equation by a fraction that's equivalent to 1, 1 * something is still the same thing. Or if we modify both sides of the equation by the same factor, the 'balance' between the two sides remains the same. The analogy with the two scales like this http://2.bp.blogspot.com/_G2nG3IQDT-8/TKqEfRO3VjI/AAAAAAAAAJo/iozqw5sr4ZQ/s1600/scales1.jpg might be a useful one.

[Eugenet17]

try eliminating variables froom the equations, and at the end i think you should end up with k can not equal to 5/3. correct me if im wrong, kinda rustyy :/

that's the right answer, but how do i eliminate x?

EDIT: nvm got it

[Only Cheating Yourself]

can someone help with a linear equation, question?

[Apink]

can someone help with a linear equation, question?

What's the question? 

[Only Cheating Yourself]

What's the question? 

solve for x

2x+29/3 =x+44/8 +2

so what i did was i found the LCD, which is 24? but anyway i the incorrect answer.

[SocialRhubarb]

Multiply both sides by 24, then collect like terms from both sides, then solve for x.

[Apink]

solve for x

2x+29/3 =x+44/8 +2

so what i did was i found the LCD, which is 24? but anyway i the incorrect answer.

Yep, the LCD is 24. So:
2x+232/24=x+132/24+48/24
2x-x=132/24-232/24+48/24
x=-52/24
x=-13/6

[Only Cheating Yourself]

Multiply both sides by 24, then collect like terms from both sides, then solve for x.

still got wrong answer

[Stevensmay]

still got wrong answer

Solve for x.


Subtract x from both sides.



Subtract from both sides.



Rewrite all fractions to have the same common denominator, which is 8*3.



Make them all into the one fraction.



Addition/subtraction.



Divide to simplify.

[b^3]

solve for x

2x+29/3 =x+44/8 +2

so what i did was i found the LCD, which is 24? but anyway i the incorrect answer.

Since normally they'd give you simplified, I'm guessing it's meant to be ? Which means you should have a set of brackets in there. It just makes it easier for everyone else and means they don't waste their time answering a question that you're not asking, just due to a lack of brackets.

This is assuming that you're saying is wrong?

[Stevensmay]

Taking b^3's alternate view.

Solve for x.



Multiply everything by 24.